Rats chewing car wiring- any ideas on preventing it?

I live in the country. When I look out my window I see 100 acres of chaparral, and beyond that, 200 acres of hay farm, and beyond that, a wildlife refuge with thousands of acres of more chaparral. Thus, we have an endless supply of rodents.

Over the last 7 years, the rats caused thousands of dollars of damage to my ‘99 Tacoma. It was, however, not a very sophisticated car, and there was only so much wiring for them to chew. I just moved up to a 2007 Mitsubishi Outlander last week, and already the rodents are storing nesting material under the hood. Aaargh! This car has a lot more wiring to chew, and it would be a lot more expensive to fix the damage.

So here are some things we have and have not tried-
Cats- Nope, they’ll be coyote bait.
Garage- Don’t have one.
Traps or poison- Futile, even if I didn’t have ethical problems with them. There are thousands more where these came from.
Mothballs, ammonia, cayenne pepper- They seem to have weak effectiveness. However, they also stink up the car, and you have to remember to remove them from the engine block before driving! What research I can find on them shows that rodents habituate to them and they do not work long-term.
Lifting the hood and hanging a light- I’m going to try this, but, of course, only some of the engine compartment will be illuminated, so I don’t think it’s 100% effective.
A fan- Another one I am going to try- it’s been suggested that the noise and vibration will scare them off. I think they may also habituate to it, though.

Anyone else have any great ideas?